Presence Of Bromide Research Articles

Electrochemical oxidation of furans into 2,5-dimethoxy-2,5-dihydrofurans

Substituted 2,5-dimethoxy-2,5-dihydrofurans (cis/trans isomer mixtures) were obtained via the electrochemical oxidation of the corresponding furans in an undivided cell in methanol in the presence of bromides as mediators. The method is suitable for furans containing electron-donating groups.

Molecular characterization of nontarget brominated disinfection byproducts formed during the ozonation in the presence of bromide and ammonium and their potential toxicity implications

While there is extensive literature covering byproducts formed during various water treatment processes, there is limited research focusing on the generation of brominated disinfection byproducts (Br-DBPs) specifically during ozonation in the presence of bromide (Br−) and ammonium (NH4+). This study used Orbitrap mass spectrometry and a custom halogen extraction code to selectively pinpoint 109 Br-DBPs generated during the ozonation of Suwannee River natural organic matter (SRNOM) containing Br− and NH4+. The Br-DBPs are predominantly distributed ranging from m/z 190 to 320, with elemental compositions consisting of CHOBr and CHONBr. They mainly fell within the H/C (0.5–1.5) and O/C (0.2–1.0) zones, with 16 % being aromatic compounds. NH4+ suppressed Br-DBP formation in CHOBr1-2 subgroups but promoted it in CHONBr1-2 subgroups compared to Br−-containing SRNOM ozonation. Kendrick mass defect diagram revealed 64 identical Br-DBP formulas in the CHOBr1-2 subgroups in both systems, and among them, 13 brominated carboxylic acids were identified, whose formation was suppressed by the addition of NH4+. Moreover, bromonitrophenol and bromobenzonitrile were identified in CHONBr1-2 subgroups, and their formation pathways were proposed. Nitrogen-containing Br-DBPs, especially the aromatic nitrogen-containing ones, exhibited higher toxicity. Caution is necessary to minimize toxic Br-DBPs formation during Br− and NH4+-involved ozonation. This study offers insights into Br-DBP characterization, formation mechanisms and toxicity, guiding enhanced water treatment strategies.

Magnesium(II) porphyrazine with peripherally overloaded pyrrolyl substituents – Synthesis, optical and electrochemical characterization

Cross-coupling Suzuki-Miyaura reaction using Microwave Assisted Organic Synthesis (MAOS) approach of phenylboronic acid and magnesium(II) porphyrazines with peripheral dimethylamino and 3,4-dibromo-2,5-diphenylpyrrol-1-yl or 3-bromo-2,4,5-triphenylpyrrol-1-yl groups led to magnesium(II) porphyrazines with dimethylamino and 2,3,4,5-tetraphenylpyrrol-1-yl groups. MAOS approach was also used in the Paal-Knorr reaction to synthesise the modified diaminomaleonitrile intermediates. All intermediates and macrocycles were characterized using UV-Vis, 1H and 13C NMR spectroscopy, as well as ES or MALDI MS spectrometry. The optical and electrochemical properties of obtained porphyrazine macrocycles were assessed. It was found that the susceptibility of new macrocycles to oxidation/reduction processes analyzed by cyclic and differential pulse voltammetry depended on the presence of bromide and the number of phenyl substituents in the macrocyclic periphery.

Electrokinetic potential of precipitates obtained from CuSO4, alkali halides, and NaOH

The precipitates obtained from CuSO4, alkali halides, and NaOH consist chiefly of brochantite Cu4SO4(OH)6. The precipitate obtained in the presence of chloride contains also atacamite. The dispersions of pale green particles at pH > 10 turn brown within several hours. The particles show pH-dependent surface-charging similar to that shown by metal oxides, and their IEP is at pH about 9, and it is independent of nature and concentration of 1-1 electrolyte. The electrokinetic curves in the specimens precipitated in the presence of bromide and iodide at pH < 7 were atypical: at high ionic strengths the positive ζ potentials dropped as the pH decreased.

Sunlight enhanced the formation of tribromomethane from benzotriazole degradation during the sunlight/free chlorine treatment in the presence of bromide

The coexistence of free chlorine and bromide under sunlight irradiation (sunlight/FC with Br−) is unavoidable in outdoor seawater swimming pools, and the formation of brominated disinfection byproducts could act more harmful than chlorinated disinfection byproducts. In this study, benzotriazole was selected as a model compound to investigate the degradation rate and the subsequent formation of disinfection byproducts via sunlight/FC with Br− process. The rate constants for the degradation of benzotriazole under pseudo first order conditions in sunlight/FC with Br− and sunlight/FC are 2.3 ± 0.07 × 10−1 min−1 and 6.0 ± 0.7 × 10−2 min−1, respectively. The enhanced degradation of benzotriazole can be ascribed to the generation of HO•, bromine species, and reactive halogen species (RHS) during sunlight/FC with Br−. Despite the fact that sunlight/FC with Br− process enhanced benzotriazole degradation, the reaction results in increasing tribromomethane (TBM) formation. A high concentration (37.8 μg/L) of TBM was detected in the sunlight/FC with Br−, which was due to the reaction of RHS. The degradation of benzotriazole was notably influenced by the pH value (pH 4 − 11), the concentration of bromide (0 − 2 mM), and free chlorine (1 − 6 mg/L). Furthermore, the concentration of TBM increased when the free chlorine concentrations increased, implying the formation potential of harmful TBM in chlorinated seawater swimming pools.

Disinfection by-products control in wastewater effluents treated with ozone and biological activated carbon followed by UV/Chlor(am)ine processes

Sequential utilization of ozone (O3) and biological activated carbon (BAC) followed by UV/chlor(am)ine advanced oxidation process (AOP) has drawn attention in water reuse. However, the formation of disinfection by-products (DBPs) in this process is less evaluated. This study investigated the DBP formation and the relevant toxicity during the O3-BAC-UV/chlor(am)ine treatment of sand-filtered municipal secondary effluent. DBP formation in UV/chlorine and UV/dichloramine (NHCl2) processes were compared, where the impact of key operational parameters (e.g., UV wavelength, pH) on DBP formation were comprehensively evaluated. O3-BAC significantly reduced DBP formation potential (DBPFP) (58.2 %). Compared to UV/chlorine AOP, UV/NHCl2 AOP reduced DBP formation by 29.7 % in short-time treatment, while insignificantly impacting on DBPFP (p > 0.05). UV/NHCl2 AOP also led to lower calculated cytotoxicity (67.7 %) and genotoxicity (55.9 %) of DBPs compared to UV/chlorine AOP. Compared to 254 nm UV light, the utilization of 285 nm UV light decreased the formation of DBPs in wastewater treated with the UV/chlorine AOP and UV/NHCl2 AOP by 31.3 % and 19.2 %, respectively. However, the cytotoxicity and genotoxicity in UV/NHCl2 AOP using 285 nm UV light increased by 83.4 % and 58.5 %, respectively, compared to 254 nm. The concentration of DBPs formed in the UV/NHCl2 AOP at pH 8 was 54.3 % lower than that at pH 7, suggesting a better control of DBPs at alkaline condition. In the presence of bromide, UV/NHCl2 AOP tended to generate more brominated DBPs than UV/chlorine AOP. Overall, UV/NHCl2 AOP resulted in lower concentration and toxicity of DBPs compared to UV/chlorine AOP.

Suların Klorla Dezenfeksiyonunda Trihalometan Oluşumuna Hümik Asit ve Bromürün Etkisi

Chlorination is one of the most important methods used in water disinfection. Chlorine reacts with natural organic substances in water and causes the formation of disinfection byproducts that might cause health problems. The predominant by-product of chlorination is trihalomethanes. Humic substances, which make up the majority of natural organic substances, are the primary precursors of trihalomethanes. In this study, the effect of different doses of chlorine on the formation of chloroform, bromodichloromethane, dibromochloromethane and bromoform in the presence of natural organic matter and bromide in drinking water was evaluated. Artificial raw water samples prepared with the addition of 2, 3 and 5 mg/L humic acid representing natural organic matter were subjected to chlorination at doses of 1, 2 and 3 mg/L and analysed on the 0th, 3rd and 7th day. The only trihalomethane formed was chloroform with a concentration of 20.52-131.13 μg/L. Increased humic acid and chlorine levels resulted in increased chloroform content. Free chlorine in the water caused chloroform formation to continue even on the 7th day. Accordingly, the amount of chloroform formed increased with the contact time. While the chlorine dose was constant, increased humic acid resulted in decreased free chlorine. To evaluate the effect of bromide on trihalomethane formation, 200 μg/L bromide was added to 2 mg/L humic acid containing water, and 1 mg/L and 2 mg/L chlorination was applied. At the end of the chlorination process in bromide-free waters, only 23.46-41.90 μg/L of chloroform was formed. In the presence of bromide, chloroform, bromodichloromethane, dibromochloromethane and bromoform were formed and the total trihalomethane level increased to 50.03-85.59 μg/L. While the ratio of brominated trihalomethane increased, the amount of chlorinated species decreased.

Direct conversion of cyano group to cyanogen chloride and dichloroacetonitrile in the UV/chlorine process

The combined application of chlorination and UV irradiation has the potential to yield important benefits in water treatment. However, much of the fundamental chemistry that governs the behavior of UV/chlorine systems have not been well defined. Cyano-containing pesticides (CNPs) are widely used in agriculture and inevitably enter surface waters and other aquatic environments. In this study, twenty CNPs and their intermediates were investigated to evaluate the formation of disinfection byproducts under chlorination and UV/chlorine systems. It was found that UV/chlorine can significantly enhance the generation of cyanogen chloride (CNCl) and dichloroacetonitrile (DCAN) compared to chlorination alone. The CNCl and DCAN concentrations increased from an average of 0.13 and 0.12 μM during the chlorination alone to 0.85 and 0.41 μM, respectively, when UV254 light was introduced. The maximum yields of CNCl and DCAN could reach 31.8 % and 7.7 %, respectively. Both the photo-induced •OH and •Cl played a key role in the generation of CNCl and DCAN. Additionally, higher yields of total CNX were observed in the UV/chlorine system in the presence of bromide. Similar results were obtained in the treatment of actual water samples, in which the concentrations of CNCl and DCAN increased by orders of magnitude under UV/chlorine treatment compared to the chlorination alone. The results showed that the cyano group of organic pollutants has a higher potential to be directly converted to toxic CNCl and DCAN under UV/chlorine treatment. The inclusion of this basic chemistry will deepen our understanding of UV/chorine water treatment technologies.

Comparative formation of chlorinated and brominated disinfection byproducts from chlorination and bromination of amino acids

Amino acids are the main components of dissolved organic nitrogen in algal- and wastewater-impacted waters, which can react with chlorine to form toxic halogenated disinfection by-products (DBPs) in the disinfection process. In the presence of bromide, the reaction between amino acids and secondarily formed hypobromous acid can lead to the formation of brominated DBPs that are more toxic than chlorinated analogues. This study compares the formation of regulated and unregulated DBPs during chlorination and bromination of representative amino acids (AAs) (e.g., aspartic acid, asparagine, tryptophan, tyrosine, and histidine). In general, concentrations of brominated DBPs (trihalomethanes, haloacetonitriles, and haloacetamides, 24.9–5835.0 nM) during bromination were higher than their chlorinated analogues (9.3–3235.3 nM) during chlorination. This indicates the greater efficacy of bromine as a halogenating agent. However, the formation of chlorinated haloacetic acids during chlorination was higher than the corresponding brominated DBPs from bromination. It is likely that an oxidation pathway is required for the formation of haloacetic acids and chlorine is a stronger oxidant than bromine. Moreover, chlorine forms higher levels of haloacetaldehydes (74.4–1077.8 nM) from amino acids than bromine (1.0–480.2 nM) owing to the instability of brominated species. The DBP formation yields depend on the types of functional groups in the side chain of AAs. Eight intermediates resulting from chlorination/bromination of tyrosine were identified by triple quadrupole mass spectrometer, including N-chlorinated/brominated tyrosine, 3-chloro/bromo-tyrosine, and 3,5-dichloro/dibromo-tyrosine. These findings provided new insights into the DBP formation during the chlorination of algal- and wastewater-impacted waters with elevated bromide.

Interaction between gastric enzyme pepsin and tetradecyltrimethylammonium bromide in presence of sodium electrolytes: Exploration of micellization behavior

Pepsin is a proteolytic enzyme used in the treatment of digestive disorders. In this study, we investigated the physicochemical properties of the tetradecyltrimethylammonium bromide (TTAB) and pepsin protein mixture in various sodium salt media within a temperature range of 300.55–320.55 K with 5 K intervals. The conductometric study of the TTAB+pepsin mixture revealed a reduction in the critical micelle concentration (CMC) in electrolyte media. The micellization of TTAB was delayed in the presence of pepsin. The CMC of the TTAB + pepsin mixture was found to depend on the concentrations of electrolytes and protein, as well as the temperature variations. The aggregation of the TTAB+pepsin mixture was hindered as a function of [pepsin] and increasing temperatures, while micellization was promoted in aqueous electrolyte solutions. The negative free energy changes (∆Gm0) indicated the spontaneous aggregation of the TTAB+pepsin mixture. Changes in enthalpy, entropy, molar heat capacities, transfer properties, and enthalpy-entropy compensation variables were calculated and illustrated rationally. The interaction forces between TTAB and pepsin protein in the experimental solvents were primarily hydrophobic and electrostatic (ion-dipole) in nature. An analysis of molecular docking revealed hydrophobic interactions as the main stabilizing forces in the TTAB-pepsin complex.

Chlorination of phenol, bisphenol A, and methylparaben in the presence of bromide: Kinetic simulation and formation of brominated aromatic byproducts

The seawater intrusion caused by the rising sea level increased the bromide (Br−) levels in the source waters of coastal cities. Adding bromide could significantly improve the degradation of phenol, bisphenol A, and methylparaben by chlorine. Bromide in water was first oxidized to active bromine species, which further reacted with phenols to generate brominated aromatic byproducts. A kinetic model including the reactions of chlorine oxidizing bromide, chlorine with phenol, and active bromine with phenol was established. The reaction rate constants of active bromine with phenols were calculated by fitting the degradation of phenols by chlorine in the presence of different bromide concentrations via the kinetic model. The rate constants of active bromine with phenols (1.5 × 104 to 2.9 × 104 M−1s−1 at pH 7.0) were higher than those of chlorine with phenols (4.0 × 101 to 8.9 × 101 M−1s−1 at pH 7.0), resulting in a bromide enhancement effect. The kinetic model could accurately simulate the evolution of total oxidant concentration with time (R2 > 0.96). Various brominated aromatic byproducts were identified in the chlorine/phenols/bromide systems, and they were first produced and then further degraded by chlorine. The technology of removing bromide and phenolic components from source water should be developed to control the formation of toxic brominated aromatic byproducts.

Isopropyl‐branched lard and its potential application as a bio‐based lubricant

AbstractRegular lard (RL) was chemically modified into isopropyl‐branched lard (BL). The isopropyl group was introduced into the triglyceride structure via a reaction of carbon–carbon double with isopropyl bromide in presence of ethylaluminum sesquichloride. The reaction was confirmed with gas chromatography–mass spectroscopy, nuclear magnetic resonance, infrared spectroscopy. The physical, tribological and chemical properties of the RL, BL and their blendings in polyalphaolefin (PAO) and high‐oleic sunflower oil (HOSuO) were investigated. The BL exhibited better solubility both in HOSuO and PAO than RL. Compared to RL, BL exhibited higher density, viscosity, improved oxidative stability and cold flow properties both as a neat material and blendings in HOSuO or PAO. However, BL displayed lower viscosity index (197 vs. 162) compared to RL. Both RL and BL displayed similar lubricity as HOSuO and showed potential such as a good lubricity additive in PAO even in small amounts (~10 wt%). This study reveals introducing alkyl branching into lard can lead to improved physico‐chemical properties and lubrication performance.

Formation of halogenated chloroxylenols through chlorination and their photochemical activity.

Trace organic contaminants usually go through multiple treatment units in a modern water treatment train. Structural modification triggered by pretreatment (e.g., prechlorination) may influence the further transformation and fate of contaminants in downstream units. However, knowledge on this aspect is still limited. In this contribution, we investigated the chlorination of chloroxylenol (PCMX), an antimicrobial agent extensively used during COVID-19 pandemic, and the photoreactivity of its halogenated derivatives. Results indicate that chlorination of PCMX mainly proceeded through electrophilic substitution to give chlorinated products, including Cl- and 2Cl-PCMX. The presence of bromide (Br-) resulted in brominated analogues. Owing to the bathochromic and "heavy atom" effects of halogen substituents, these products show increased light absorption and photoreactivity. Toxicity evaluation suggest that these halo-derivatives have higher persistence, bioaccumulation, and toxicity (PBT) than the parent PCMX. Results of this contribution advance our understanding of the transformation of PCMX during chlorination and the photochemical activity of its halogenated derivatives in subsequent UV disinfection process or sunlit surface waters.

Reaction of Polyamide Membrane Model Monomers with Chlorine Dioxide: Kinetics, Pathways, and Implications.

Aromatic polyamide (PA) based membranes are widely used for reverse osmosis (RO), but they can be degraded by free chlorine used for controlling the biofouling prior to RO treatment. Kinetics and mechanisms for the reactions of PA membrane model monomers, i.e., benzanilide (BA), and acetanilide (AC), with chlorine dioxide (ClO2) were investigated in this study. Rate constants for the reactions of ClO2 with BA and AC at pH 8.3 and 21°C were determined to be (4.1±0.1)×10-1 M-1.24 s-1 and (6.0±0.1)×10-3 M-1 s-1, respectively. These reactions are base assisted with a strong pH dependence. The activation energies of BA and AC degradation by ClO2 were 123.7 and 81.0 kJ mol-1, respectively. This indicates a relatively strong temperature dependence in the studied temperature range of 21-35 °C. The presence of bromide and natural organic matter does not promote the degradation of model monomers by ClO2. BA was degraded by ClO2 via two pathways: (1) the attack on the anilide moiety with the formation of benzamide (major pathway) and (2) oxidative hydrolysis to benzoic acid (minor pathway). A kinetic model was developed to simulate the degradation of BA and formation of byproducts during ClO2 pretreatment, and simulations agree well with the experimental data. Half-lives of BA treated by ClO2 were 1-5 orders of magnitude longer than chlorine under typical seawater treatment conditions. These novel findings suggest the potential application of ClO2 for controlling biofouling ahead of RO treatment at desalination treatments.

Formation of Targeted and Novel Disinfection Byproducts during Chlorine Photolysis in the Presence of Bromide.

Chlorine photolysis is an advanced oxidation process that relies on the combination of direct chlorination by free available chlorine, direct photolysis, and reactive oxidants to transform contaminants. In waters that contain bromide, free available bromine and reactive bromine species can also form. However, little is known about the underlying mechanisms or formation potential of disinfection byproducts (DBPs) under these conditions. We investigated reactive oxidant generation and DBP formation under dark conditions, chlorine photolysis, and radical-quenched chorine photolysis with variable chlorine (0-10 mg-Cl2/L) and bromide (0-2,000 μg/L) concentrations, as well as with free available bromine. Probe loss rates and ozone concentrations increase with chlorine concentration and are minimally impacted by bromide. Radical-mediated processes partially contribute to the formation targeted DBPs (i.e., trihalomethanes, haloacetic acids, haloacetonitriles, chlorate, and bromate), which increase with increasing chlorine concentration. Chlorinated novel DBPs detected by high-resolution mass spectrometry are attributable to a combination of dark chlorination, direct halogenation by reactive chlorine species, and transformation of precursors, whereas novel brominated DBPs are primarily attributable to dark bromination of electron-rich formulas. The formation of targeted and novel DBPs during chlorine photolysis in waters with elevated bromide may limit treatment applications.

Formation and speciation of hazardous trihalomethanes and haloacetic acids during chlorinated washing of brined kimchi cabbage in the presence of bromide

Brominated disinfection byproducts (Br-DBPs) may be generated in high concentrations during the chlorinated washing of brined kimchi cabbage (BKC) in kimchi manufacturing. However, the generation of these DBPs is not sufficiently understood. Therefore, in this study, we investigated the formation and speciation of the DBPs trihalomethanes (THMs) and haloacetic acids (HAAs) during the chlorinated washing process. The average bromide content in 22 salt products sourced from various regions of Korea was 1600 ± 468 mg/kg. Increasing bromide content shifted the speciation of DBPs from chlorinated to mixed bromochloro to brominated species, which would be more harmful than their chlorinated analogs. DBP formation during the washing of BKC at average bromide levels changed based on the brine salinity, salting temperature, and disinfectant type. Based on our findings, we recommend that low salinity and low temperature should be maintained during the salting of KC and that NaOCl should be used as the disinfectant rather than slightly acidic electrolyzed water during the chlorinated washing of KC to alleviate the formation of Br-DBPs. Moreover, we recommend the use of salts with low bromide levels for the salting of KC and the addition of a rinse step after chlorinated washing.

Overlooked Contribution of the Indole Moiety to the Formation of Haloacetonitrile Disinfection Byproducts

Haloacetonitriles (HANs) are a group of disinfection byproducts with high toxicity and frequent occurrence. Past studies have focused on the free amine groups, especially those in amino acids, as HAN precursors. This study reports, for the first time, that the indole moiety such as that in the tryptophan side chain is also a potent precursor for the most common HANs dichloroacetonitrile, bromochloroacetonitrile, and dibromoacetonitrile. 3-Indolepropionic acid, differing from tryptophan only in the absence of the free amine group, formed HANs at levels 57-76% of those by tryptophan at a halogen/nitrogen molar ratio of 10. Experiments with tryptophan-(amino-15N) showed that the indole contributed to 28-51% of the HANs formed by tryptophan. At low oxidant excess (e.g., halogen/precursor = 5), 3-indolepropionic acid even formed more HANs than Trp by 3.5-, 2.5-, and 1.8-fold during free chlorination, free bromination, and chlorination in the presence of bromide (0.6 mg/L), respectively. Indole's HAN formation pathway was investigated by exploring the chlorination/bromination products of 3-indolepropionic acid using liquid chromatography-orbitrap high-resolution mass spectrometry. A total of 22 intermediates were detected, including pyrrole ring-opening products with an N-formyl group, 2-substituted anilines with different hydroxyl/halogen substitutions, and an intermediate with a postulated non-aromatic ring structure.

Photo-transformation of acetaminophen sensitized by fluoroquinolones in the presence of bromide

Fluoroquinolones (FQs) are a class of antibiotics with emerging concern. This study investigated the photochemical properties of two representative FQs, i.e., norfloxacin (NORF) and ofloxacin (OFLO). Results showed that both FQs could sensitize the photo-transformation of acetaminophen under UV-A irradiation, during which excited triplet state (3FQ*) was the main active species. In the presence of 3 mM Br‾, the photolysis rate of acetaminophen increased by 56.3% and 113.5% in the solutions with 10 μM NORF and OFLO, respectively. Such an effect was ascribed to the generation of reactive bromine species (RBS), which was verified by 3,5-dimethyl-1H-pyrazole (DMPZ) probing approach. 3FQ* reacts with acetaminophen through one-electron transfer, producing radical intermediates which then couple to each other. Presence of Br‾ did not lead to the formation of brominated products but the same coupling products, which suggests that radical bromine species, rather than free bromine, were responsible for the accelerated acetaminophen transformation. According to the identified reaction products and assisted with the theoretical computation, the transformation pathways of acetaminophen under UV-A irradiation were proposed. The results reported herein suggest that sunlight-driven reactions of FQs and Br‾ may influence the transformation of coexisting pollutants in surface water environments.

Comparison of UV/chloramine disinfection of methylamine water in the absence and presence of bromide: Halonitromethanes formation, toxicity alteration, and reaction mechanisms

UV/chloramine is considered a new potential disinfection process to substitute traditional disinfection methods, and the participation of bromide (Br−) significantly influences halonitromethanes (HNMs) formation during UV/chloramine disinfection. Herein, the formation laws of HNMs from methylamine were explored and compared during UV/chloramine disinfection with and without the existence of Br−. The results indicated that there were similar formation laws of HNMs between the disinfection processes with and without the existence of Br− but different species and productions of HNMs were observed. Furthermore, both the total HNMs productions during UV/chloramine disinfection with and without the existence of Br− were markedly enhanced when increasing chloramine dosage while those were significantly reduced when increasing solution pH from 6.0 to 8.0. Also, it was pointed out that Br− dramatically strengthened the toxicity of HNMs, and the toxicity alteration of HNMs was consistent with the changes in the yields of total HNMs with reaction time. Meanwhile, the reaction mechanisms of HNMs formed from methylamine were speculated during UV/chloramine disinfection with and without the existence of Br−, and Br− presented a non-negligible impact on the formation mechanisms. Finally, the formation laws of HNMs in two real water samples were found to be similar to that in simulated water samples during UV/chloramine disinfection, while different species and yields of HNMs were simultaneously observed. This work illustrated HNMs formation from methylamine and the significant impacts of Br− on HNMs generation during UV/chloramine disinfection.

Synthesis of oxidovanadium complexes containing coumarin and naphthalene: bromoperoxidase activity and DNA/BSA binding

Two tridentate Schiff base ligands, L1 and L2 , have been introduced in the synthesis of mononuclear oxidovanadium complexes with a co-ligand 1,10-phenanthroline. Two mononuclear complexes, [VO(L1)(1,10-phen)] (1) and [VO(L2)(1,10-phen)] (2), have been synthesized in high yields by reactions with [VO(acac)2] in 1:1 ratio in methanol under reflux with 1,10-phenanthroline as co-ligand. X-ray crystallographic studies unveil the structures of 1 and 2 showing L1 and L2 bind in O^N^O coordination. The complexes were characterized by using UV-Vis, IR, NMR and Mass spectral techniques. The physiochemical properties have been interpreted by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. The mimicking of vanadium haloperoxidase was investigated by bromination of phenol red in the presence of bromide and H2O2 with a rate of 2.68 × 102 (mol/L)−2 s−1. The DNA and BSA protein binding interactions of 1 and 2 have been explored by UV–Vis and fluorescence spectral methods; viscosity measurements reveal that the complexes interact with CT-DNA through intercalation in the order [VO(L1)(1,10-phen)](2.71 × 104) > [VO(L2)(1,10-phen)](9.67 ×103). The complexes exhibit binding interactions with BSA protein.